Loud-speaking telephone



April 13- ,,1 25. 1,580,517

' R. E. MARBURY LOUD SPEAKING TELEPHONE Filed Nov. 28, 1923 WITNESSES:

Ralph. E. Mar-burying is a speifioation.

Patenledlpr. 13, 1926 UNITED STATE RALPH n. IARIBUBY, or rrrrsn'une'n, rmusnvmm, assrenon. 'ro mart n rA'nzu'r iOFFlLCE.

ELECTRIC & HANUI'ACTUBINGCOMPANY, A QQBPORATION 0F PENNSYIKVLIIA.

LOUD-SPEAKING TELEPHONE. I

' A'pphcatlo'n flled November-28,1223. Serial No. 677,564.

4e- Armatures and To all whom a 0mm Be it known that I, RALPH E. MARBURY,

a. citizen of the United States, and a resident. of .Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Loud- Speaking Telephones, of-which the follow-- My vention relates to apparatus for the production of loud sounds. l

Broadly speaking, the object of my invention is to produce sound of great-volume corresponding to a relatively electric current.

Another object of my invention is to produce an amplified soundcorresponding to a vibratory electric current;

A further object of my invention is to amplify the ener of a vibratory electric current during the procedure of converting the vibratory electric-current energy into sound.

Another object of my invention is'to supply energy for amplification of the energy contained in a vibratory electric current by the addition of further errirgy obtained from a mechanically rotating y; f

In practicin 'my invention, I provide a diaphragm, a or'n, a shaft and means'ior rotating it, an electromagnet for converting varying electric currents into a varying magnetic flux, andmeans under the control of the magnetic fluxffor producing a varying torque from the rotating shaft. I then vi- 'brate the, diaphragm by means of this varying torque, producing sound thereby, which sound is directed and controlled by the horn.

Other objects" and structural details -of my invention will be apparent from the followin description when read in connection with t e accompanying drawing, wherein:

Thesingle figure 1s a diagrammatic sketch,

partly. in section, of my invention.-

In the figure is, shown a horn 1 attached to a' supporting framework 2. '-Framework 2 carriesa ring mount 3 in which is sup--- ported a. diaphragm 4. Both horn'and ring are carried on a support 5 which, in turn, is attached to a base late 6. On the same base late 6 is moun an electric'motor 7 having a shaft 8 andlead wires 9.

' A friction drum 11is mounted u n the;

"sh'aft8. A-brake band 12 surroun s drum 11. An arm 13 isattached to brake band 12. A 14 connects the'end of'arm 133170 the center of diaphra smallvibratory suitable energy source for the 7.,

16 are attached to brake band12. An electromagnet 17 with a permanent magnet core 18 is positioned between armatures '15 arid -16. Conductors 19 connected to electromag net 17 lead to asource-of vibratory electric-' surrounds current energy. 21 encloses the evice."

The motor 7 may be of any constant speed type and it-may be adapted to run at any desired voltage, either'latrbe greater than a few watts, since theactual power required for my device is Conductors 19 are attached to the source of vibratory electric-current ener which it is desired to convert into soun Th s may, if so desired, be the output-ofa radio detector system, or it may be a, telephonic connectionto any other source of vibratory electric current which it is desired to into sound. With the motor .7 runningat normal speed, and no current traversing-opu- 7 ductors 19, a definite amount OffllGtiOlk occurs between drum 11 and brake band .12,

by reason of thepull of permanent magnet core 18, which is substantially constant in value ,and produces a constant torque in the brake band. This constant torque is converted into a steady pull upondiaphragm 4 through the agency of arm 13,1111

14. Accordingly, the diaphragm does not vibrate and no sound is produced.

A steady current flowing in conductors 19 will produce an increase or a decrease in the magnetic pull on the armatures 15 and 16, depending on the direction of the current. .This will result in a change in the ressure of brake band 12 upon drum 11, there altering'the torqne developed and the pu upon the center of diaphragm 4, but no sound will beprodueed. A I

A vibrato current supplied to conductors 19.and coil will, however, produce a varying attraction for armatures 15 and 16 thereby producing a varying amount oi drod" friction between brake band 12 and drum 11- response to a smaller amount of vibratory electrical energy supplied to conductors 19.

A considerable portion of the energy is obtained from the energy of rotation of shaft 8 Hand. motor 9 and, therefore, is correspondingly supplied from the electrical imput of leads 9. 1 r In practice, this mechanism makes it possible to produce relatively loud sounds from a relatively weak vibratory current.

Whilev I have shown only one embodiment "of my invention in the accompanyingdrawings, it is capable of various changes and modifications without departing from thespirit thereof, and it is desired, therefore,

t at only such limitations shall be imposed v thereon as are indicated in the prior art or" in the appended claims.

I claim as my invention:

1. A loud speaking telephone device comprising a diaphragm, a horn, a rotating drufm, a friction band on said drum, a progecting arm, attached to said band, a link etween said diaphragm and said arm, armatures of magnetic material attached to the ends of said band, an electromagnet adjacent to said armatures, and a source of signal frequency current connected to said magnet,

2. A sound reproducing device, comprising a horn, a diaphragm, and means for producing vibrations in said diaphragm, said means comprising a rotating drum, a friction band on said drum; means for converting the torque conveyed to said band into a pull on said diaphragm, and means comprising armaturesrespectively attached to the ends of said band and an electromagnet cooperating therewith for varying the friction ,pressure between said drum and said band,

and a source of variable electric current for exciting said electromagnet.

3. In a sound-reproducing device, an exciting source of variable electric current, a

constant-speed source of mechanical energy,

means comprising a friction band and a drum driven by said mechanical energy for obtaining a torque from said energy, means comprising a bar and link for converting said torque, into a tangential pull, means comprising an electromagnet, and armatures attached to sand frlct-ion band for varying saidtorque 1n response to\the variation in variations of said tangential 'pull into sound.

In testimony whereof, I have hereunto subscribed my name this 14th day of November, 1923.

, RALPH E. MARBURY.

- said exciting current, and means comprising i a diaphragm and horn for converting the 

